Cooling/Fan Shroud

[MOPARJ]

I am currently trying to locate the correct fan shroud for my 73 Duster, 318, originally an a/c car, so it has the wide 26” radiator. There is a shroud on it currently, but I don’t believe it is correct. The fan is fully underneath the should, not halfway out/halfway in as most have told me it should be. Any feedback on this? If not correct, any leads to locate the correct one would be great. Low speed cooling is suffering currently and the fan clutch itself is no problem. Radiator is ok as well, along with tstat. Temps come up to about 200-205 at highway speeds on a 75-80 degree day, 215-220 resting or moving slowly.

Water pump will be replaced this weekend (50k miles on current unit).

 

[autoxcuda]

What is the part number on your current shroud?

Could be the viscous fan clutch is putting the fan in the wrong position. I'm not sure all factory fan to shroud are 100% half in half out.

 

[AJ/FormS]

Put a 5 or more blade,direct drive fan on first, and pop the stat out and put a restrictor washer in there instead, and crank the initial timing up to at least 10*BTDC(prove the dizzy is working, including the V-can);to see whats what.
What kinda Rs is she spinning at at "highway speeds"?
Running hot at highway speeds is not likely to be a shroud issue. More likely to be airflow through the rad or heat transfer in the rad itself, assuming the stat is fully opening.
Running hot at idle is most likely a clutch problem, or very late ig.timing.
So go back to the first sentence.If it still overheats, ditch the rad.
A stock 318 or even mildly hopped up, without A/C,properly timed, and a good rad,doesnt need a shroud.
In my experience, somewhere between 35 and 45 mph, in high gear,the cooling fan is overpowered by ram air into the rad. So below that speed the fan system has to be working. Above that speed, not so much. Look at the tiny rad windows the Nascar guys are running at near 200mph.And a tiny piece of paper stuck on the front can ruin their day.

 

[ir3333]

clutch fans are not the best set up....only turn about 80-90% of crank speed and quite often will run a little warmer when idling.
I have solved a few lo speed cooling problems by installing a quality fixed blade fan or even a quality flex fan rated for for 5000 rpm +
i'm going to take a bit of heat for this (no pun intended)but i'm not convinced a shroud does much.

 

[AJ/FormS]

I kinda agree about the shroud.
In my experience they can be helpful on systems that arent working at their best or on undersized systems.Or maybe in hot climates. But up here in Canuck-land,IDK. Ive had lots of As that didnt have them or need them.
A 26"rad on a 318 is certainly not undersized.
I have a 430 hp 360 with a 26"rad and shroud. The shroud is only on there cause I had it at the time I put it together. Im sure it would cool just fine without it. I did have a bit of a problem with a flexfan and will never run one again. I also had troubles with a couple of different non-thermostatic viscous clutches, and wont run those either.Then one day I found the Ford thermo-clutch. It works perfect. The reason its on there is because I heard a mid-2000 Ford truck one day coming into the shop where I was working, with the thermo kicking in and out. Wow, I said! I gotta have that .And you may or may not know this; that Ford fan was huge. Almost Mac-truck huge compared to our Mopar fans. I got one. It bolted right on. And um no, you cant have it. No PN,sorry. I have 2 perfectly good, slightly used oem-type clutch fans, shelved.

 

[krazykuda]

but i'm not convinced a shroud does much.

Wrong. Shrouds are important! :wack:


They help funnel the air so that the fan can move it better and greatly increase cooling.

It does no good to have a radiator if you can't get air to flow through it... They need airflow to work...

 

[krazykuda]

http://www.manciniracing.com/rafansh.html

 

[MOPARJ]

http://www.manciniracing.com/rafansh.html

Thanks, but it is a 26" radiator, and a 73.

 

[MOPARJ]

For fixed fan selections, what is a good brand and compatible with the water pump pulley I have at the moment? I currently have the existing a/c water pump pulley.

 

[ir3333]

if you have your fan an inch from the rad it will pull air through it efficiently.
most mopar shrouds don't really improve flow here because a lot of them actually block flow through the sides and corners....now a chevy benefits from a shroud because a lot of them have the fan 5 or 6 from the rad.
..i have no first hand experience here but try to think about what makes sense.

 

[AJ/FormS]

Moparj
-If you have a 6 or 7 blade fan already, for a viscous clutch,theres no point in trashing a good fan. Take it(the fan) and your pulley down to your favorite parts house. Ask for a thermostatic Ford clutch fan to fit a mid-2000 or so F-150 or F-250. One of those thermo clutches will absolutely work.You can recognize the thermo clutch by the little coil spring mounted on the hot side. The coil is wound into a spiral like a clock-spring.
-There is one caveat; if the air that is passing through the rad is not hot, it will not activate the coil and valve. And Im almost fully persuaded that your rad is not doing its job. If your car was here, I would be taking it out and bringing it to the rad shop for evaluation.Our local rad shop has never let me down.
-Just FWIW, there are chemicals you can buy to clean out your rad.When used as directed they can do a good job. Sometimes however, they can work too good, by removing the deposits which are actually plugging holes. Then you have a holy rad(batman).Or a rad with holes.Or if several holes, I guess it would be wholey holed. Or wholey holey. Anyway......then its off to the rad shop anyway. And youre out the cash for the treatment.
-So, I guess what Im saying is this; maybe the first thing to do would be to get the rad checked out. If the rads bad, changing the other stuff may not help, or will be a temporary fix. If the rads good, then you can move ahead with the fan change or a thermo fan

 

[mderoy340]

Take your lower radiator hose off. Hold your hand over the opening and fill the radiator with water. Remove hand; if it has good flow it should empty like a toilet.